I want to have a clean start with a Mac Mini (late 2012) that has Yosemite right now. At the same time, I want to delete the existing Apple ID associated to the machine. What is the best way? I would like to keep Yosemite, but maybe it is not possible. I did not see anything in App store, and I don't know what OS version it originally had.
What I have done so far:
Opened the case and ready to put SSD
Ran Time Machine to backup to external USB drive
It sounds that somewhere I need to de-authorize the computer from iTune.
And I have a feeling that I need to make a USB bootable to install the latest Sierra from scratch onto SSD.
If all of this is very time consuming, then I could just upgrade the OS to the Sierra, and transfer all to SSD. I am a Windows guy, and I am used to reinstalling Windows OS every 3-5 years, to speed it up. How does Mac work? Upgrading to the latest Mac OS would give it a fresh start?
Lastly, if something goes wrong, can I restore all from the external USB drive? I don't even know what format it is in. I just did a few clicks to make it available for Time Machine.